music21 v. 1.5 Released

A new version of music21 has been released, the first public release since January.  This release focuses primarily on speed and stability improvements so it is worth an upgrade even if none of the new features is of use to you.  A summary of what's new:

1. Many improvements to Layout -- information soon, but pixel level positioning of measures can now be extracted from MusicXML files.
2. Chordify addPartIdAsGroup=True works better.
3. Better triplet handling in Humdrum SpineParser.
4. Some .nwc files (not just .nwctxt) files can now be parsed.
5. Improvements for PartStaffs (Piano scores, etc.)
6. .transpose works on Key objects.

Thanks to everyone for support and new ideas on where to take the project.